DS Kessel said: "We have arrested a 49-year-old male on suspicion of murder. He is believed to be known to Gaia and is from the Swanage area.

"We have been conducting this inquiry for two weeks and it's our responsibility to explore every avenue of inquiry. That's important to us.

"We continue to investigate whether Gaia has come to harm through an act of crime or whether she is missing."

Image:CCTV images of Gaia Pope have been released by Dorset Police

He said the search would likely continue "for some time" but that it was a "fast moving investigation" and there was "no reason to believe" Gaia had left the Swanage area. He refused to describe the investigation as a murder inquiry.

Police are also said to be pursuing "a number of other avenues of investigation".

He continued: "I would like to offer my thoughts and thanks to her family, who are going through an incredibly distressing time.

"I would also like to thank the public, particularly of Swanage and the local community, who have been incredibly supportive and understanding of the police operation into Gaia's disappearance."

The owner of the clothes found earlier on Thursday has not been identified, police said, but detectives involved in the search for Gaia have informed her family of the find.

The teenager, from Langton Matravers, was staying at an address in Swanage when she disappeared. She was wearing grey and white woven leggings, white trainers and a red checked shirt with white buttons.